From Kook Science

Pythagoreanism is a religious and philosophical system based on the teachings of Pythagoras of Samos (c. 570-495 BC), an ancient Ionian Greek philosopher active in the Achaean city of Kroton, and his inheritors, including Philolaus of Croton (c. 470-385 BC) and Archytas of Tarentum (c. 425-350 BC). The views of the Pythagoreans are predicated on the understanding that the ultimate reality is arithmós, the Number, and mathematical form is therefore key to understanding the metaphysical absolute; from this, they proceed to beliefs in the sacredness of proportion and harmony, as well as certain mathematical symbolism and theorems, and to the musica universalis (resonance of planetary motion as music), metempsychosis (transmigration of the immortal soul, reincarnation), and other related concepts.